Photofermentative hydrogen production from molasses: Scale-up and outdoor operation at low carbon-to-nitrogen ratio

Savasturk D., Kayahan E., KOKU H.

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, vol.43, no.26, pp.11676-11687, 2018 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 43 Issue: 26
  • Publication Date: 2018
  • Doi Number: 10.1016/j.ijhydene.2018.01.014
  • Journal Name: INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.11676-11687
  • Keywords: Photofermentation, Rhodobacter capsulatus, Molasses, Carbon-to-nitrogen ratio, Scale-up, Outdoor, RHODOBACTER-SPHAEROIDES OU-001, SOLAR TUBULAR PHOTOBIOREACTOR, PHOTOSYNTHETIC BACTERIA, BIOHYDROGEN PRODUCTION, DARK FERMENTATION, LIGHT-INTENSITY, CAPSULATUS, PHOTOPRODUCTION, METABOLISM, DESIGN
  • Middle East Technical University Affiliated: Yes

Abstract

Photofermentative hydrogen production was carried out under outdoor conditions with a Rhodobacter capsulatus strain on molasses, a renewable and sustainable feedstock. An existing photobioreactor design was scaled-up from 9 L to 20 L. The decreased carbon-to nitrogen (C/N) ratio of 13.0, compared to our previous work, accelerated growth and resulted in a reduced lag period for hydrogen production as well as higher productivities in the exponential phase. However, the low C/N ratio also promoted a high optical density due to growth, limiting light transmission. Still, the maximum productivity was found as 0.47 mol H-2/(m(3).h), significantly higher than our result with the smaller reactor volume. High rates of production could not be maintained presumably due to the combined effects of cloudy periods, the aforementioned C/N ratio and decreasing pH. These results suggest that the scale-up was successful and there is potential for further improvement using optimal C/N ratio and cell concentration values. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.